立式乙苯过热器泄漏原因分析及改造措施

Cause analysis of vertical ethylbenzene superheater leakage and revamping measures

海南实华嘉盛化工有限公司80 kt/a苯乙烯装置脱氢反应系统采用π-L结构型式,由于乙苯过热器内漏造成脱氢反应产物中苯乙烯质量分数由62%降至56%左右。分析泄漏原因为乙苯过热器自身倾覆力矩过大和出口膨胀节失效产生的应力使膨胀节失效,造成乙苯过热器筒体下部产生塑性变形所致。针对性地采取了乙苯过热器整体更换以及更换出入口膨胀节等改造措施。改造后乙苯过热器的倾覆力矩由450 kN·m下降到122 kN·m,化验分析数据表明,脱氢液与脱氢反应产物中的乙苯、苯乙烯含量基本一致,苯乙烯质量分数稳定在60%左右,说明乙苯过热器严重内漏的现象已经消除,有利于装置的节能以及精馏系统的操作优化。

The"π-L"structure has been adopted for the dehydrogenation reaction system of 80,000 TPY styrene unit of Hainan Shihua Jiasheng Chemical Co.,Ltd.. Because of ethylbenzene superheater leakage,the styrene content in dehydrogenation products went down from 62% to about 56%. The cause analysis concluded that the main causes of leaking of ethylbenzene superheater are the plastic deformations of the lower part of ethylbenzene superheater which occurred because of expansion joint failure of ethylbenzene superheater outlet. The whole ethylbenzene superheater and the inlet and outlet expansion joints were replaced. After revamping,the overturning moment of the superheater went down from 450 kN·m to 122 kN·m. The laboratory data showed that the contents of ethyl benzene and styrene in the dehydrogenated liquid are constant with those in dehydrogenation reaction products. The percentage of styrene is maintained at about 60%,which indicates that the serious internal leaking of ethylbenzene superheater has been eliminated. It is beneficial for energy saving and operation optimization of the fractionation system.